[ADD] inventory: How to use routes ?

https://docs.google.com/document/d/1ee5b8BF9ywG-TKAAgTjGWbm7tDZ6agV7rEmiosQPuwo/edit#heading=h.4vcpc1gho0vv

inventory/routes/concepts/use_routes.rst

@@ -1,3 +1,154 @@
 ==================
 How to use routes?
 ==================
+
+Overview
+========
+
+A route is a collection of procurement rules and push rules. Odoo can
+manage advanced push/pull routes configuration, for example:
+
+-   Manage product manufacturing chains
+
+-   Manage default locations per product
+
+-   Define routes within your warehouse according to business needs, such
+    as quality control, after sales services or supplier returns
+
+-   Help rental management, by generating automated return moves for
+    rented products
+
+Configuration
+=============
+
+Procurement rules are part of the routes. Go to the **Inventory**
+application, :menuselection:`Configuration --> Settings` and tick 
+**Advance routing of products using rules**.
+
+.. image:: media/use_routes01.png
+    :align: center
+
+Pre-configured routes
+=====================
+
+Odoo has some pre-configured routes for your warehouses.
+
+In the Inventory application, go to 
+:menuselection:`Configuration --> Warehouses`.
+
+In the **Warehouse Configuration** tab, **Incoming Shipments** and **Outgoing
+Shippings** options set some routes according to your choices.
+
+.. image:: media/use_routes02.png
+    :align: center
+
+Custom Routes
+=============
+
+In the **Inventory** application, go to 
+:menuselection:`Configuration --> Routes`.
+
+.. image:: media/use_routes03.png
+    :align: center
+
+First, you have to select the places where this route can be selected.
+You can combine several choices.
+
+Routes applied on warehouses
+----------------------------
+
+If you tick **Warehouses**, you have to choose on which warehouse it will
+be applied. The route will be set for all transfer in that warehouse
+that would meet the conditions of the procurement and push rules.
+
+.. image:: media/use_routes04.png
+    :align: center
+
+Routes applied on products 
+---------------------------
+
+If you tick **Products**, you have to manually set on which product it
+will be applied.
+
+.. image:: media/use_routes05.png
+    :align: center
+
+Open the product on which you want to apply the routes 
+(:menuselection:`Inventory --> Control --> Products`). 
+In the Inventory Tab, select the route(s):
+
+.. image:: media/use_routes06.png
+    :align: center
+
+Routes applied on Product Category
+----------------------------------
+
+If you tick **Product Categories**, you have to manually set on which
+categories it will be applied.
+
+.. image:: media/use_routes07.png
+    :align: center
+
+Open the product on which you want to apply the routes
+(:menuselection:`Configuration --> Product Categories`). 
+Select the route(s) under the **Logistics** section :
+
+.. image:: media/use_routes08.png
+    :align: center
+
+Routes applied on Sales Order lines
+-----------------------------------
+
+If you tick **Sales order lines**, you have to manually set the route
+every time you make a sale order.
+
+.. image:: media/use_routes09.png
+    :align: center
+
+In order to make it work, you also have to activate the use of the
+routes on the sales order.
+
+In the Sales application, go to 
+:menuselection:`Configuration --> Settings` and tick
+**Choose specific routes on sales order lines (advanced)**.
+
+.. image:: media/use_routes10.png
+    :align: center
+
+You can now choose the routes for each lines of your sales orders:
+
+.. image:: media/use_routes11.png
+    :align: center
+
+Procurement and push rules
+==========================
+
+Please refer to the documents:
+
+-  :doc:`procurement_rule`
+
+-  :doc:`push_rule`
+
+Procurement configuration
+=========================
+
+When doing a procurement request, you can force the route you want to
+use. On the product (:menuselection:`Inventory Control --> Products`), 
+click on **Procurement Request**. Choose the route you want to use next to
+**Preferred Routes**:
+
+.. image:: media/use_routes12.png
+    :align: center
+
+Make-to-Order Route
+===================
+
+If you work with no stock, or with minimum stock rules, it is better to
+use the **Make To Order** route. Combine it with the route **Buy** or
+**Manufacture** and it will trigger automatically the purchase order or
+the Manufacturing Order when your products are out-of-stock.
+
+.. seealso::
+    * :doc:`push_rule`
+    * :doc:`inter_warehouse`
+    * :doc:`cross_dock`